10/16/2024
By Lynne Schaufenbil

Please join the Lowell Center for Space Science and Technology on Thursday, Oct. 17, at 11 a.m., for the virtual seminar, "Segment-level Sensitivity Analysis for Imaging Earth-like Planets," by Ananya Sahoo.

Abstract:
Imaging and characterizing Earth-like planets, or exo-Earths, is a key scientific objective of the Habitable Worlds Observatory (HWO), as identified by the NASA 2020 Astrophysics Decadal Survey. Earth-like planets are extremely faint bodies and are typically located at close angular separation of their host stars, making their direct imaging a significant challenge. Achieving this requires optimized coronagraphs capable of 10^-10 starlight suppression and picometer-level of wavefront stability. Several factors such as optical aberrations, phasing errors, observatory vibrations, and thermal drifts pose considerable risks to pm-level of wavefront stability. In this talk, I will present methodologies to compute wavefront stability requirements for an arbitrarily segmented-space telescope architecture. In particular, I will focus on building a contrast-sensitivity matrix which relates the coronagraphic dark-hole contrast to wavefront aberrations, and invert this matrix to obtain static tolerances required for exo-Earth imaging. I will compare the requirements thus obtained across different primary mirror (PM) architectures comprising varying segment sizes and numbers. In a realistic observing scenario, such as the presence of quasi-static wavefront errors, dynamic tolerance values are required to compensate for drifts and maintain a stable dark hole. To address this, I will translate the static tolerance coefficients obtained into the time domain using a simple batch-estimation algorithm, which integrates wavefront error estimation from models of segmented PM, deformable mirrors (DMs), a low read-noise science camera and a non-common-path Zernike wavefront sensor to predict the closed-loop tolerances. This work constitutes a step towards a complete understanding of optical stability tolerances and optimizing error budget allocations for exo-Earth coronagraphy.

Short Bio:
Dr. Ananya Sahoo is a Staff Scientist at the Space Telescope Science Institute (STScI). Her current research focuses on studying wavefront-errors induced by thermal disturbances for future segmented space telescopes, as well as infrastructure development for the HiCAT testbed. Dr. Sahoo earned her Ph.D. in 2020 from The Graduate University for Advanced Studies, SOKENDAI, in alliance with National Astronomical Observatory of Japan (NAOJ). Previously, she contributed to the photometric and astrometric calibration for the SCExAO instrument at the Subaru Telescope. Her work aims to advance our understanding of exoplanet direct imaging and improve the capabilities of next-generation high-contrast imaging instruments.

If you are interested in attending, please email Lynne_Schaufenbil@uml.edu for the Zoom link.